Back in April, Louisville's WDRB posted an affecting story about Louisville Gardens, the former Jefferson County Armory, which opened in 1905. It has sat vacant for decades. Louisville Gardens was added to the National Register of Historic Places in 1980, though that hardly speaks to what the building means to Derby City, even as a vacant arena.

WDRB's Marcus Green waxes poetic:

The building where civil rights icon Rev. Martin Luther King Jr. spoke?

It's a city storage facility.

The building that sheltered Louisville residents forced from their homes during the 1937 flood?

Its entrance is cluttered with chairs.

The building that held a public memorial after the Titanic sank in 1912?

Two windows on the main Muhammad Ali side are boarded.

The city's Economic Growth and Innovation Department has looked to develop the property, but efforts have stalled recently while the city focuses on another downtown parcel.

Louisville Gardens is the most prominent of the city's distressed public properties—but there are thousands, all told, including vacant lots. A new venture called OpportunitySpace aims to make it easier for developers to find these potential investment opportunities—and for residents to figure out who owns the distressed or vacant properties in their communities.

According to CEO and cofounder Alex Kapur, OpportunitySpace is an "information-rich marketplace that enables real-estate development and investmenet in place-based projects." The website uses data provided by cities to populate a map, which shows users information about properties at a variety of levels.

"The missing link between plans and people who invest is that communication layer," says OpportunitySpace vice-president and cofounder Cristina Garmendia. "You don’t know what you don’t know."

OpportunitySpace offers filters for users looking for different kinds of properties as well as for users looking for information about specific properties.

The project, which started as Kapur and Garmendia's masters theses at Harvard's Kennedy School, is now public (in beta). Today, OpportunitySpace is expanding to four cities in Rhode Island: Central Falls, Pawtucket, Cumberland, and Providence. Louisville was the first city to work with OpportunitySpace to map its vacant, disused, and distressed properties.

The project got its first big push after Kapur met with U.S. Environmental Protection Agency officials to discuss how better data could improve brownfield remediation. The EPA linked him up with Ted Smith, chief of Louisville's Economic Growth and Innovation Department.

Winners in Louisville's "Lots of Possibility" contest, in one map.

OpportunitySpace aims to offer four tiers of information and analytics about participating cities: zoning, planning information, incentives, and available development. But the site can accommodate special development programs, too. For example, the Louisville portal maps the winners of the recent "Lots of Possibility" effort, a contest for communities to plan new uses for vacant lots.

City data on inventory are often "frozen in amber," Garmendia says. Usually it takes a real reform effort to make these data public and useful—or even move the records from paper to digital. "Someone in the private sector decides to do their tour of duty in the public sector, and then they’re appalled," she says.

Specific inventory listings include address info, images, and even parcel history, where possible.

Garmendia says that the Rhode Island portal includes a type of property that none of the four cities has reliably listed online: privately-owned tax-delinquent properties. There are about 350 such properties in Providence's database, for example, but these properties only come onto the market at tax auctions. Garmendia says that these are in fact available for purchase year round—there's just no obvious marketplace for them. "They would just do the auction once a year, and otherwise forget about it," she says.

As for privacy concerns: These data are publicly available, Kapur says. They're just not publicly accessible. In Louisville, he notes, the records on Louisville Gardens amount to a single sheet of paper, which the city would send to interested would-be developers.

"Data can range in any given jurisdiction from highly digitized, clean, accessible databases to bits of knowledge living in people’s heads that we have to go in and extract by interview," Kapur says.

Listing pages also include key links or documents for property information.

OpportunitySpace also means to digitize and map planning documents that often take the form of PDFs—documents that are not streamlined between departments. There's an option on the site to filter, for example, for information on the River Corridor Development program, a joint effort between the cities of Pawtucket and Central Falls that otherwise exists online as a PDF.

Garmendia and Kapur are looking to raise capital over the next 8 months as they scale up to 6 or 7 cities. The site would ostensibly generate revenue through premium tools, including analytics, geared toward real-estate developers, private-equity funds, municipal bond underwriters, and others. It's also a service for cities, where, the founders say, the departments collecting taxes aren't talking enough with the departments attracting investors.

According to Kapur, OpportunitySpace works because cities themselves are getting involved in development. They aren't waiting around in Louisville for a Louisville Gardens buyer to show up. "The technology that we’re developing reflects cities' proactive posture related to redevelopment," he says. "Louisville actually found us."